LF Group,
Again, thanks to SV8RV DF2JP PA7EY and DF6NM for the reports.
In my last post I reported the drift was constrained to within 1 Hz.
This should be 1 mHz. Thanks Markus for your assurances that this
should be adequate for EbNaut which I hope to use to send send our
cat's name on LF. The little curls appear often on the QRSS traces on
your high res spectra. Doppler variations were removed from the 10 MHz
WWV signals with harmonic regression when the DOCXO was calibrated
so this effect is seen on LF but not as strongly.
After reading about EbNaut on Paul Nicholson's pages it seems I have
much catching up ahead. Fasinating stuff!
Can the EbNaut phase inversions be done without an absolute time
reference? I'm cheap and lazy so hoping GPS will not be needed.
The Opera will be doing an encore tonight and if the wind stays low
a tower climbing expedition is planned for the afternoon.
73
Joe VO1NA
On Sat, 7 Nov 2015, Markus Vester wrote:
Hi Joe, LF,
during the last couple of nights, opds detected all of your transmissions
between about 22 and 7:30 UT.
Attached is a zoomed 40 mHz section from my opds-32 spectrogram, showing your
central coherent carrier which contains half of the transmitted average power.
It seems to be about 0.5 mHz below 137477 Hz (possibly due to a calibration
error in my receiver). The 2.7 mHz spaced sidelines during the early part
(bottom) were caused by 6-minute-periodic interruptions from my own MF WSPR
transmissions. However the little curls near the carrier can presumably be
attributed to Doppler-shifted multipath components. The carrier was still
weakly visible for another hour after the last detection.
Comparing the looks of the carrier to earlier IZ7SLZ transmissions, the
stability of the signal and the path seems quite sufficient for half-hour
EbNaut PSK transmissions. Unfortunately I missed the opportunity to save the
raw data and analyze phase evolution using the EbNaut decoder itself - will try
that next time.
All the best,
Markus (DF6NM)
From: [email protected]
Sent: Saturday, November 07, 2015 12:03 AM
To: [email protected]
Subject: Re: LF: last night opera opds detection in km07ks
LF Group,
I am grateful to Joe DF2JP for his captures QRSS and Opera
Dionysious SV8RV for his OP decodes to Domenico IZ7SLZ
for his OPDS decodes, and thanks to DF6NM for opds!
I do not know if my DOCXO is stable enough for EbNaut.
It was set a couple of years ago and has not drifted more than
1 Hz since then. It seems the phase decoherence has stopped
haunting me.
I am hoping to replace the halyard for the other 100m wire soon.
OP32 again tonight as send this email.
73
Joe
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